In the field of color management, a color profile comprises a set of data that characterizes a color space, such as for a color output device, wherein the color profile is often based on standards set by the International Color Consortium (ICC).
FIG. 1 illustrates a visible colorspace, i.e. spectrum, including colors represented within the visible colorspace, e.g. red, orange, yellow, green, blue, indigo, and violet. Also shown in FIG. 1 is an RGB color gamut, and a CMYK color gamut. For example, devices, images and designs can be defined by an RGB color gamut, based on red (R), green (G), and blue (B). As well, some devices, images and designs can be defined by a CMYK color gamut, based on varying amounts of cyan (C), magenta (M), yellow (Y), and black (K).
As FIG. 1 shows, the RGB color gamut can approximate some but not all colors within the visible spectrum. Display devices, such as computer monitors and television screens, can operate within an RGB color spectrum, such as with red, green and blue elements that can be powered at different intensities.
As also shown in FIG. 1, not all colors in an RGB color gamut can be represented in a CMYK color gamut, which is commonly used for output devices, e.g. printers. In addition to the use of cyan, magenta, yellow, and black toners or inks, some printing systems allow the use of white or other spot colors.
Color profiles for output devices allow color management systems to convert color data between color spaces, such as between a device independent color space and a native device color space, or between device color spaces. The ICC specifies color profiles for input devices, display devices, and output devices.
White spot color, which can be used as a special spot color channel within some printing systems, is not included in the creation of an ICC profile when using commercial ICC profiler software. Thus, neither a media color nor the white ink channel are used to match possible colors correctly. Thus, the media color may be such that it is not possible to print a desired color on such media because it would be necessary to print colors that are not within the print device gamut if the printed image is to compensate for the effect on the image created by the media color.
Commercial ICC profiler software expects brighter media color than inks, and inks must have chromaticity and transparency. This is not provided with a printing system that offers white ink. White ink has neither chromaticity nor transparency, and colored media is darker than the white ink. As such, white ink cannot be processed inside commercial and common ICC profiler software. In practice white ink is only used to cover colored media, and then 4-channel CMYK ink is printed on top of that white ink layer.